The present invention relates to a waterproof button switch, especially to a waterproof button switch with leakage proof ring.
FIG. 1 shows a prior art button switch comprising a switch mount 2a and a base 1a. The switch mount 2a has a stage 21a and a cap 22a arranged thereon. The base 1 a has a hole 11a with an inner surface 12a. The cap 22a has relative movement with the inner surface 12a and has relative movement with a vertical groove (not shown) in the stage 21a. The cap 22a has a recess 23a on a circumference thereof and a leakage proof ring 3a (such as an o-ring) is embedded into the recess 23a. The leakage proof ring 3a has circular cross-section and slides along the inner surface 12a of the base 1a. 
The leakage proof ring 3a is made of flexible material such as rubber. When droplet accidentally insets into the hole 11a, the droplet is accumulated atop the leakage proof ring 3a. The leakage proof ring 3a may have problem of twisting during operation of the button switch and is expanded or shrunk with temperature variation. As a result. the droplet accumulated atop the leakage proof ring 3a has the risk of leaking into the switch mount 2a and damaging a circuit board (not shown) of the switch mount 2a. In other word, the leakage proof ring 3a cannot provide tight seal for the button switch.
It is the object of the present invention to provide a waterproof button switch with leakage proof ring.
In one aspect of the present invention, the button switch has a leakage proof ring having a tail portion bent to have surface contact with an inner wall a hole receiving a cap of the button switch. The tail is bent to form an accommodation space for storing droplet accidentally flowing into the hole.
To achieve above object, the present invention provides a waterproof button switch having a switch mount and a base. The switch mount has a stage and a cap arranged thereon. The base has a hole with an inner surface. The cap as relative movement with the inner surface and also has relative movement with the stage. The cap has a recess with rectangular cross-section on a circumference thereof and a leakage proof ring is embedded into the recess. The leakage proof ring has an inner semi-segment and an outer semi-segment. The inner semi-segment has rectangular cross-section for fitting into the recess. The outer semi-segment is slantingly extended from an outer surface of the inner semi-segment and has a triangular cross-section, the outer semi-segment comprises a tail having surface contact with the inner surface of the hole.